/**
* Copyright (C) 2013-2024 Nanjing Pengyun Network Technology Co., Ltd.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/ 

package py.common.lock;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

public class HashLockImpl<T> implements HashLock<T> {
  private final ConcurrentHashMap<T, AtomicInteger> locks = new ConcurrentHashMap<>();

  @Override
  public void lock(T val) throws InterruptedException {
    for (; ; ) {
      AtomicInteger waitingCount = locks.computeIfAbsent(val, v -> new AtomicInteger(0));
      synchronized (waitingCount) {
        if (waitingCount == locks.get(val)) {
          int waiting = waitingCount.getAndIncrement();
          if (waiting != 0) {
            waitingCount.wait();
          }
          return;
        }
      }
    }
  }

  @Override
  public boolean tryLock(T val) {
    AtomicInteger waitingCount = locks.putIfAbsent(val, new AtomicInteger(1));
    return waitingCount == null;
  }

  @Override
  public void unlock(T val) {
    AtomicInteger waitingCount = locks.get(val);
    synchronized (waitingCount) {
      int waiting = waitingCount.decrementAndGet();
      if (waiting != 0) {
        waitingCount.notify();
      } else {
        locks.remove(val);
      }
    }
  }

}
